Tensile strength of human dentin as a function of tubule orientation and density.
Tensile strength of human dentin as a function of tubule orientation and density.
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发表时间：
2001
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通讯作者：
R. Carvalho;C. Fernandes;R. Villanueva;Linda Wang;D. Pashley
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作者：
R. Carvalho;C. Fernandes;R. Villanueva;Linda Wang;D. Pashley
目的研究人牙本质的极限抗拉强度(UTS)与牙本质小管取向和密度的关系。材料与方法取人第三磨牙牙冠，用等位锯进行横切或纵切，得到厚度约0.7 mm的牙本质板条。轻轻地修剪牙板，将冠状牙本质的中心面积减少到约0.5mm2的横截面面积。从近侧和远侧或从咬合和牙髓方面修剪纵向切断板，以允许拉伸载荷平行或垂直于小管方向施加。在距牙髓几个距离处获得横切面标本，并用于评估小管密度的影响。在Kratos试验机上以0.5 mm/min的速度对修剪后的试件进行拉伸测试。故障后，计算每个部件的UT并以兆帕表示。横断面标本断端在扫描电子显微镜下观察，计算断口每平方毫米的小管数，并用回归分析探讨其与UTS的关系。结果当载荷垂直于小管方向时，牙本质的UTS(80+/-13 Mpa)高于平行于小管方向时(58+/-11 Mpa，p0.05)。结论牙本质的UTS与小管方向有关。随着单位面积小管数的增加，牙本质逐渐变弱。
PURPOSE This study investigated the ultimate tensile strength (UTS) of human dentin as a function of tubule orientation and density. MATERIALS AND METHODS Slabs of dentin (ca 0.7 mm thick) were obtained from human third molars by either transversally or longitudinally sectioning the crowns with an Isomet saw. The slabs were gently trimmed to reduce the central area of the coronal dentin to a cross-sectional area of approximately 0.5 mm2. The longitudinally sectioned slabs were either trimmed from the mesial and distal sides or from the occlusal and pulpal aspects to permit the tensile load to be applied either parallel or perpendicular to the tubule orientation. The transversally sectioned specimens were obtained at several distances from the pulp and were used to evaluate the effects of tubule density. The trimmed specimens were tested in tension on a Kratos testing machine at 0.5 mm/min. After failure, the UTS of each was calculated and expressed in MPa. The fractured ends of the transversally sectioned specimens were viewed under SEM to calculate the number of tubules per mm2 at the site of fracture, and its relation with the UTS was investigated by regression analysis. RESULTS The UTS of dentin is higher when the load is applied perpendicular to the tubule orientation (80 +/- 13 MPa) than when applied parallel to tubule orientation (58 +/- 11 MPa, p 0.05). CONCLUSION The UTS of dentin is dependent on the tubule direction. Dentin tends to be weaker as the number of tubules per area increases.